BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:4
UID:UW-Physics-Event-9834
DTSTART:20261012T170000Z
DTEND:20261012T180000Z
DTSTAMP:20261104T064108Z
LAST-MODIFIED:20261005T120429Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Parity-Time Symmetry of Plasma Waves\, Plasma Physics (Physics
 /ECE/NE 922) Seminar\, Hong Qin\, University of Wisconsin-Madison
DESCRIPTION:The susceptibility tensor of a homogeneous collisionless m
 agnetized plasma possesses parity-time (PT) symmetry. For a stationary
  gyrotropic equilibrium\, with the wave vector $\\mathbf{k}$ and the e
 quilibrium magnetic field $\\mathbf{B}_0$ in the x-z plane\, the kinet
 ic response satisfies $\\chi(\\omega^\,\\mathbf{k})=R\\chi(\\omega\,\\
 mathbf{k})^R$\, where $R=\\operatorname{diag}(1\,-1\,1)$. We show that
  the susceptibility PT-symmetry is a reduced-response-space manifestat
 ion of PT symmetry of the underpinning kinetic system. We identify par
 ity P and time reversal T on the complete electromagnetic kinetic eige
 nmode space and show that the Hamiltonian operator $\\mathcal{H}_{\\ma
 thrm{VM}}$ of the linearized Vlasov--Maxwell system is PT-symmetric\, 
 satisfying $PT\\mathcal{H}_{\\mathrm{VM}}(PT)^{-1}=\\mathcal{H}_{\\mat
 hrm{VM}}$. The corresponding PT symmetry of the homogeneous magnetized
  Vlasov--Poisson eigenproblem is also established. Many kinetic instab
 ilities associated with nonmonotonic distributions\, rings\, loss cone
 s\, and resonant energetic-particle populations are fundamentally spon
 taneous PT-symmetry breaking\, which is achieved through and only thro
 ugh Krein collisions. Three examples demonstrate distinct utilities of
  this analysis. Definite-sign cyclotron residues protect thermal Berns
 tein modes from spontaneous PT-symmetry breaking. The nonmonotonic Dor
 y--Guest--Harris distribution permits sign-indefinite residues and Kre
 in collisions\, for which we derive an analytical instability threshol
 d and growth rate. The recently discovered mode-pole resonance instabi
 lity provides a distinct realization of spontaneous PT-symmetry breaki
 ng and illustrates how PT symmetry can guide the discovery of kinetic 
 instabilities with applications to fusion energy. These results establ
 ish PT symmetry as a structural principle of plasma waves and instabil
 ities and open new directions for studying spectral topology in kineti
 c plasmas. 
URL:https://www.physics.wisc.edu/events/?id=9834
END:VEVENT
END:VCALENDAR